Discovery of sperm defect raises hopes of male contraceptive pill that mimics it

A breakthrough by fertility researchers could help hundreds of men achieve their dream of fatherhood and also raises hopes of producing a male contraceptive pill.

Oxford University researchers have pinpointed a genetic defect that prevents sperm from fertilising eggs.

A drug that corrects the problem could help 600 couples a year in the UK alone become parents, while one that mimics the flaw could be used to create a male pill.

The discovery centres around a protein called PLC zeta which is passed from the sperm to the egg on fertilisation, triggering the creation of new life.

Some men are infertile because their sperm fails to 'awaken' the egg. The research could one day be used to create a male contraceptive

Researcher Dr John Parrington said: 'An egg cell before fertilisation is in a state of suspended animation.

'All the biological processes that occur in the growth and development of an embryo are on pause.

'At the moment of fertilisation, when a sperm fuses with the egg, the egg bursts into life. It's like a Prince waking Sleeping Beauty.'

Working with Belgian and American researchers, he studied sperm samples from nine men undergoing a common IVF procedure called ICSI, in which the sperm is injected directly into the egg.

In each case, the sperm failed to 'awaken' the egg and the treatment was unsuccessful.

Tests showed problems in the with PLC zeta protein produced by the men. One made a defective form, others die not make enough or it was stored in the wrong part of the sperm, the journal Human Reproduction reports.

Co-researcher Dr Kevin Coward said: 'We have found that some men are infertile because their sperm fail to activate eggs.

'Even though the sperm fuses with the egg, nothing happens. The sperm lack a proper functioning version of the PLC zeta protein involved.'

Further experiments showed that it is possible to activate eggs by injecting them with the gene that makes the protein, raising hopes of a new fertility drug.

Dr Parrington said: 'This was a lab experiment and our method could not be used in a fertility clinic in exactly the same way.

'But in the future, if we could produce the PLC protein artificially, we could stimulate egg activation in a completely natural way.

'For those couples going through IVF treatment where ICSI has failed, it could give them the chance of a baby.'

In fertile men, a drug that blocks the protein could be used as a contraceptive.

Dr Parrington said: 'Now we know that this one protein is absolutely critical at the point where life begins, we can think about finding drugs that stop this protein acting.

'While this discovery is just an initial step and there is no guarantee of success, a targeted male pill that would not have any of the side effects of the female pill is a tantalising prospect.'

Infertility affects one in six couples at some point in their lives - and 30 to 50 per cent of the problems are with male partner.

Problems with the PLC protein will only account for a small proportion of these but could still add up to 600 cases a year.

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Discovery of sperm defect raises hopes of male contraceptive pill that mimics it